1. Field of the Invention
The present invention relates to a fiber reinforced cement composition using a hydraulic inorganic material such as cement, products thereof and a manufacturing process thereof.
2. Description of the Related Art
Hitherto, asbestos has been used as a reinforcing material of fiber reinforced cement products. Recently, however, woody reinforcements such as wood flakes and wood fibers have come to be used instead of conventional asbestos since environmental pollution (such as pneumoconiosis) caused by flying of fine powder of asbestos has become a serious problem.
However, fiber reinforced cement products reinforced with woody reinforcements have many problems in regard to dimension stability, handling performance and bending strength.
Thus, a special woody reinforcement such as needle-leaves-tree pulp has recently been used as the woody reinforcement, and various cement additives have been studied in order to activate development of strength not only via a hydration reaction of cement but also via a reaction between a silicate component and a calcium component.
For example, JP-3245487 B and JP4-187552 A disclose adding a specified amount of a polyvinyl alcohol resin powder to a hydraulic composition; JP2001-287980 A discloses adding a polyvinyl alcohol having specific physical properties; JP11-322395 A discloses adding a silicate having a specified Blaine value; JP6-329457 A discloses adding mica powder to a hydraulic composition; JP5-124845 A discloses adding mica coated with a polyvinyl alcohol resin; JP2002-166406 A discloses adding a specific mica; and JP2000-264701 A discloses adding a specific fiber and a specific inorganic foam.
Incidentally, the Blaine value represents fineness of a powder and refers to a specific area measured by a permeability method (Blaine permeability method).